1. Field of the Invention
The present invention relates to a reflective liquid crystal display (LCD) apparatus.
2. Description of the Related Art
LCD apparatuses are divided into light penetration type LCD apparatuses requiring backlights and reflective LCD apparatuses reflecting environmental light.
In the reflective LCD apparatuses, in order to obtain high display quality, the effeciency of reflecting and scattering environmental light is important. Also, since available environmental light is limited, the loss of light has to be reduced. Particularly, in a colored LCD apparatus using color filters, the loss of light is large.
In a prior art reflective LCD apparatus (see Naohito Kimura, "Colored Reflection type LCD", Semiconductor World, pp. 108-112, February 1995), inverted staggered thin film transistors (TFTs) where gate electrodes are beneath amorphous silicon layers are formed on a glass substrate. Further, a photosensitive acrylic resin layer having an uneven surface is formed on the TFTs. Also, pixel electrodes made of aluminum are formed on the photosensitive acrylic resin layer and each of the pixel electrodes are connected to one of the source electrodes. A counter glass substrate is prepared, and a transparent common electrode is formed on the glass substrate.
After orientation processes including orientation layer coating processes and rubbing processes are performed upon the two substrates, the two substrates are adhered to each other with a predetermined spacing therebetween, and a liquid crystal layer is then inserted into this spacing. This will be explained later in detail.
In the prior art reflective LCD apparatus, since the photosensitive acrylic resin layer has an uneven surface, the pixel electrodes also have uneven surfaces, so that the pixel electrodes serve as optical reflecting means as well as optical scattering means. Therefore, the scattering characteristics of reflected light can be improved to make the brightness of reflected light uniform over a broad visual angle. In addition, since the pixel electrodes are formed over the TFTs, effective use can be made of reflected light, thus increasing the numerical aperture. Further, if guest-host (G-H) liquid crystal which does not require polarization plates is used, a brighter display can be obtained.
In order to manufacture the prior art reflective LCD apparatus, however, a large number of photolithography and etching processes are required due to the complex configuration of the pixel electrodes, thus increasing the manufacturing cost.